Field of the Invention
The present invention relates to manufacture of wire screens for oil, gas, and water well pipe. More particularly, the present invention relates to a system and method for manufacturing wire screens for pipes.
Description of the Related Art
Hydrocarbons are produced by drilling into subterranean hydrocarbon-bearing formations. Unconsolidated formation walls can result in sand, rock, or silt accumulating in a wellbore, which can ultimately cause various problems in the drilling operation. Sand control has become increasingly important in the industry.
Well screens (also called filters) used in sand control applications can be of various types, including wire mesh and continuous slot, wire wrapped. Continuous slot, wire wrapped screens are composed of wire helically wrapped around multiple support ribs to form a cylindrical screen with a continuous helical slot there between. It is important that slot size (i.e., width between adjacent segments of the wrapped wire) is maintained within determined tolerances throughout the length of the screen.
Wire wrapped screens are typically manufactured using wire wrapping machines that simultaneously wrap the wire around, and weld the wire to, multiple support ribs, to form a hollow, cylindrical well screen of a desired length. A headstock spindle rotates the ribs causing wire to be wrapped around the set of ribs. Typically, a precision lead screw progresses the work piece laterally by driving the tailstock laterally away from the headstock. Rate of rotation of the headstock spindle in relation to advancement of the lead screw along the linear axis determines the dimensions of slot openings between adjacent wire segments.
Commercially utilized wire wrap screen machines incorporate computer based controls using servomotors for headstock spindle rotation. Typically, a servomotor with a precision ball screw controls linear movement of the driven tailstock. Alternative commercially utilized machines incorporate a helical gear rack for linear drive of the tailstock.
Some of the factors affecting the ability to maintain required slot spacing and tolerance are the relatively long sections of wire wrap screen necessary, and component wear over time. Wire wrap pipe screen sections may be greater than forty feet in length.
Linear induction drive technology has been previously described. See, for example, U.S. Pat. No. 3,824,414 issued to Laithwaite, et al., and U.S. Pat. No. 4,230,978 issued to Gardella, Jr., et al., both of which are incorporated herein by reference in their entirety to the extent not inconsistent herewith. Linear encoder technology has been previously described. See for example, U.S. Pat. No. 3,090,896 issued to Bowden, et al., and U.S. Pat. No. 3,427,518 issued to Cloup, both of which are incorporated herein by reference in their entirety to the extent not inconsistent herewith.
Embodiments of the present invention provide a wire wrap screen system having a linear induction drive system and a linear encoder system to controllably drive the tailstock, and a method for operating the wire wrap system.